Polyenealdehydes and process for preparing such compounds



United States Patent 2,812,354 POLYENEALDEHYDES AND PROCESS FOR PREPARING soon COMPOUNDS Otto Isler, Marc Montavon, and Rudolf Riiegg, Basel, and Paul Zeller, Neuallschwil, Switzerland, assignors to Hotfmann-La Roche Inc, Nutley, N. J., a corporation of New Jersey g No Drawing. Application August 10, 1955, Serial No. 527,645

Claims priority, application Switzerland August 16, 1954 13 Claims. (01. 2se s9s The process in accordance with the invention is characterized by the fact that an aldehyde of the formula in which the aldehyde group may be acetalized, is subjected to a Wohl-Ziegler reaction Ecf. C. Djerassi, Chem. Reviews, vol. 43 (1948), page 271] and the halogen compound formed is heated with a tertiary base, as a result of which hydrogen halide is split 0E with allyl rearrangement. i

The aldehydes used as follows:

4- [2',6,6'-trimethyl-cyclohexen-( 1 -yl] -2-methyl-buten- By glycide ester synthesis of ,B-ionone and chloroacetic ester, followed by treatment of the glycide ester with alkali.

as starting materials are prepared now U. S. Patent No. 2,730,549, issued January 10, 1956).

0ctatrien-(2,4,6) -al-(1 cyclohexen (1)-yl] 2,6 dimethyl octadlene (4,6)-'

ether (3) acetal (1) Produced is heated at 100 C. with acetic acid and sodium acetate, thus eifecting hydrolysis and the splitting "off of alcohol (see copending 2,812,354 Patented Nov. 5, 1957 application Ser. No. 435,936, filed June '10, 1954, now U. S. Patent No. 2,730,549, issued January 10, 1956).

The acetals are prepared from the aldehydes in accordance with known methods, for instance with orthoformates (see copending application Ser. No. 435,936, filed June 10, 1954, now U. S. Patent No. 2,730,549, issued January 10, 1956. i i Y i l The first step in accordance with the invention consists of the halogenation of the initial aldehyde or acetal at the methylene group of the side chain. The halogenation is effected in the known manner in accordance with the Wohl-Ziegler reaction. There is preferably used for this purpose N-bromosuccinimide or N-bromoacetamide in an inert solvent such as carbon tetrachloride, chloroform, benzene, methylene chloride, etc. It is particularly advantageous to work in methylene chloride at a temperature of between 0 and 30 C. The halogenation agent is preferably used in an excess of approximately 10%. The reaction can be accelerated by the addition of catalysts, such as dibenzoylperoxide, or by irradiation with light. When N-bromosuccinimide is used, sodium bicarbonate and calcium oxide are advisedly added to the reaction mixture. After completion of the reaction, which takes 15 minutes to 4 hours depending on the temperature, the mixture is filtered and the solvent, if desired, is removed in vacuum.

The halogen compounds obtained in this manner, which have the following probableformula (in which X has the same meaningas above) quinoline, pyridine, dimethylaniline, collidine, etc., and

by heating the mixture. Preferably heating is effected with quinoline for 2 to 6 hours in a nitrogen atmosphere at C. i Y

The reaction mixture is advisedly worked up by the addition of ice cold excess dilute acid and extraction of V the product with an Organic solvent, for instance petroleum-ether.

In the acid treatment, a partially saponified.

The products of the general formula cetal groups can be entirely or (in which X has the same meaning as above) obtained are purified in the customary manner, for instance by. distillation, crystallization or chromatographic treatment. They have characteristic absorption maxima in the ultraviolet spectrum. Due to the cis-trans-isomerism at the double bond, there are various spatial forms of these aldehydes or acetals; thus in'the case of 6 [2',6',6 trimethyl cyclohexen (2) ylidenel- 4 methyl hexadien (2,4) al (1) two different phenylsemicarbazones are isolated. The following table contains a summary of the phenylsemicarbazones corre- 3 sponding to the aldehydes formed in accordance with the invention:

Phenylsemicarbazones of the aldehydes Ultraviolet absorption max iron in petroleum-ether Melting point;,0.

Max. m E1 4-[2',6,6'-trimethyl-cyclohexen- (2) -y1ldene]-2-methy1-buten- (2)-nl-(1 160461 339; 354 1, 870; l, 590 6-[2,6,6-trimethyl-cyclohexen- (2) -y1idene) -4-methyl-hexadlen-(2,4)-al-(1):

(Al 184-186 366; 386 2, 330; 2, 160 (B) 164-l66 362; 382 2,140, 1,800 8-[2 6',6-trimethyl-cyclohexen- (2 )-ylidsne]-2,6-dlmethyl-octatrlen-(2.4,6)-al-(1) 198-201 372.5; 393; 1, 690; 2, 575; 416. 5 2.360

The aldehydes which can be prepared in accordance with the invention or their acetals represent valuable intermediates for the preparation of carotenoids such as for instance 4,4-dioxycarotene and bisdehydro-fi-carotene [nomenc]. according to Karrer, see Chem. and Eng. News: 24 1235-6 (1946) 4-[2,6',6-trimethylcyclohexen- (2' ylidene] -2-methyl-buten- (2 -a1- 1) and its acetals have pleasant fragrances and can therefore be used as components in perfume mixtures (see copending applications Ser. Nos. 553,211 and 553,217, both filed December 15, 1955).

The 6-[2',6,6- trimethyl-cyclohexen-(Z) -ylidene]-4- methyl-hexadien-(2,4)-al-(1) can be converted into 8 [2,6',6- trimethyl cyclohexen (2') ylidene] 2,6- dimethyl-octatrien-(2,4,6)-al-(1) in the following manner: it is acetalized by means of ethylorthoformate in the presence of a small amount of p-toluene sulfonic acid; the diethylacetal produced is thereupon condensed with ethylpropcnyl ether in the presence of zinc chloride; the 8- [2',6',6'-trimethyl-cyclohexen-(2) ylidenel -2,6-dimethyl-octadiene-(4,6)-ether-(3)-acetal-( 1) obtained is heated with.acetic.acid and sodium acetate at 100 0, whereby 8'- [2',6,6-trimethyl-cyclohexen- 2) -ylidene 2,6-dimeth3 l-octatrien-(2,4,6)-al (1) is formed by hydrolysis and splitting off of alcohol (see copending application Ser. No. 527,647, filed August 10, 1955).

The 4- [2',67,6'- trimethyl-cyclohexen-(2)-ylidene]-2- methyl-buten-(2)-al-(1),. in the same reaction but with the use of ethylvinylether instead of ethylpropenylether, gives 6 [2',6',6-trimethyl cyclohexen (2)-ylidene] 4- methyl-hexadicn(2,4)-al-(.1) (see copending aplica'tion Ser. No. 527,646, filed August 10, 1955).

EXAMPLE 1 30 parts by weight 4-[2',6',6'-trimethyl-cyclohexen- (1')-yl]-2-methyl-buten-(2)-al- (1) in 210 parts. by weight of methylene chloride are cooled with 13.5 parts by weight sodium bicarbonate and 9 parts by weight calcium oxide to C. while stirring. There are then added 28 parts by weight N-bromosuccinimide and the temperature is maintained for 3 hours at to 10 C. by intermittent cooling. The mixture after some timeassumes a yellow to red color and then becomes slowly colorless again. It is thereupon filtered, 30 parts by weight of quinoline are added, and the methylenechloride is removed in vacuum. Thereupon 30lparts by Weight quinoline are again added and the mixture is warmed for 2 hours under nitrogen on a steam bath. 350 parts by Weight .of petroleum-ether (B. P. 30 to 60 C.) are then added, followed by pouring over 250 parts by weight of B'N sulfuric acid and ice while stirring. The insoluble resin is filtered off and also the aqueous layer is removed and the petroleum-ether solution is washed, once with water, once with dilute sodium bicarbonate solution and once with Water again. After the drying of the petroleum-ether solution over sodium sulfate and concentration, 29.4 parts by weight crude 4-[2,6',6-trimethyl-cyclohexen-(2')- ylidene]-2-methyl-buten-(2)-al-(1) are obtained; this product is distilled for its purification in a Hickmann flask at a high vacuum; B. P.o.os C. A completely pure product is obtained if the compound is again distilled in a Vigreaux column (30 cm.). The aldehyde forms a yellow, thinly liquid oil, n =1.6152; ultraviolet maximum at 318 ml; E1 1610 (in petroleum-ether).

EXAMPLE 2 34 parts by weight 6-l2',6,6'-trimethyl-cyclohexen- (1')-yl]-4-methyl-hexadien-(2,4)-al-(1) are treated in the manner indicated in Example 1 in 210 parts by weight methylenechloride with 13.5 parts by weight sodium bicarbonate, 9 parts by weight calcium oxide and 28 parts by weight N-bromosuccinimide, the bromination temperature being 20 to 25 C. in contradistinction to Example 1. There are obtained 19 parts by weight of a crude product, which is purified by chromatographic adsorption. on SO-times the quantity of aluminum oxide (deactivated with 2% water) with petroleum-ether and petroleumether-ether mixtures. The 6-i2',6',6-trimethyl-cyclohexen-(2')-ylidene]-4-methyl-hexadien-(2,4)-al-(1) obtained in this manner is a mixture of isomers. By crystallization from petroleum-ether at -70 C. there can be obtained a form in yellow prisms, melting point 73 to 74 C. ultraviolet maxima 353 [fl 4., E1 2360; 372 m E1 2200 (in petroleum ether). The oily isomer can be in part transformed into the crystalline isomer by heating for 5 hours at C. with acetic acid and sodium acetate; by repeated treatment of the mother liquors, practically the entire quantity can be obtained in the form of the crystalline isomer. I 7

EXAMPLE 3 a 40 parts by weight 8-[2,6',6-trirnethyl-cyclohexen-( 1')- yl] -2,6-dimethyl-octatr ien-(2,4,6)-a1-(1) are treated, in the manner indicated in Example 1, in 210 parts by weight methylene chloride with 13.5 parts by weight sodium bicarbonate, 9 partsby .weight calcium oxide and 28 parts by weight N-bromosuccinimide, the bromination temperature, ditfering from Example 1, being 25 to 30 C. There are obtained 22 parts by weight of a crude product which is purified by chromatographic absorption. The 8 [2',6,6- trimethyl cyclohexen (2') ylidene] 2,6- dimethyl-octatrien-(2,4,6)-al(1) obtained has two maxima in the ultraviolet absorption spectrum, namely: 382 my, E1 1615; 403 ma E1 1445.

EXAMPLE 4 20.5 parts by weight of 4-[2,6',6'-trimethyl-cyclohexen- (1')-yl]-2-methyl-1,l-diethoxy-butene-(l) in parts by weight methylene chloride are cooled to 0 C. while stirring, with 6.75 parts by weight sodium bicarbonate and 4.5 parts by weight calcium oxide. There are then added 14 parts by weight N-bromosuccinimide and one thereupon proceeds in the manner described in Example 1. The crude product before the distillation is heated for 3 hours on a steam bath. with parts by weight glacial acetic acid, 15 parts by weight sodium acetate and 7 parts by weight of water in order to completely saponify the acetal. Thereupon it is diluted with 1,000 parts by Weight of water and extracted with petroleum ether and the petroleum ether layer is thereupon washed with dilute sodium bicarbonate solution and water. After the drying of the petroleum-ether solution over sodium sulfate and evaporation, there are obtained 29.1 parts by weight of crude 4-[2,6',6'-trimethyl-cyclohexen-(2)-ylidene]-2- methyl-butcn-(2)-al-( 1).

1. A process which comprises halogenating by means of an N-haloamide a member of the group consisting of 4 [2,6,6'- trirnethyl cyclohexen (1') yl] 2 methylbuten (2) al (1), 6 [2,6,6- trimethyl cyclohexen- (1) yl] 4 methyl hexadien (2,4) a1 (1), 8 [2',6,6-

trimethyl cyclohexen (1') yl] 2,6 dimethyl octatrien (2,4,6) a1 (1) and acetals thereof and heating the halogen compound formed with a tertiary base thereby dehydrohalogenating with concomitant allyl rearrangement.

2. A process which comprises halogenating by means of an N-haloamide a member of the group consisting of 4 [2,6',6'- trimethyl cyclohexen (1') yl] 2 methylbuten (2) al (1), 6 [2',6,6-trimethyl cyclohexen- (1') yl] 4 methyl hexadien (2,4) al (1),8 [2,6,6'- trimethyl cycloheXen (1') yl] 2,6 dimethyl octatrien (2,4,6) al (1) and acetals thereof.

3. A process which comprises heating with a tertiary base a compound selected from the group consisting of 4 [2',6,6- trimethyl cyclohexen (1) yl] 2 methylbuten (2) a1 (1), 6 [2,6,6-trimethyl cyclohexen- (1) yl] 4 methyl hexadien (2,4) al (1),8 [2,6,6- trimethyl cyclohexen (1) yl] 2,6 dimethyl octatrien (2,4,6) a1 (1) and acetals thereof, said compounds halogenated on the side chain, to produce, respectively, a member of the group consisting of 4-[2',6',6'-trimethyl cyclohexen (2) ylidene] 2 methyl buten- (2) al (1), 6 [2',6',6'- trimethyl cyclohexen (2')- ylidene] 4 methyl hexadien (2,4) al (1) and 8-[2, 6',6- trimethyl cyclohexen (2') ylidene] 2,6 dimethyl octatrien (2,4,6) al (1).

4. 6 [2,6,6- trimethyl cyclohexen (2') ylidene]- 4 methyl hexadien (2,4) a1 (l).

5. A process as in claim 1 wherein the halogenating agent is N-bromosuccinimide.

6. A process as in claim 1 wherein the halogenating agent is N-bromoacetamide.

7. A process as in claim 3 wherein the tertiary base is quinoline.

8. A process which comprises halogenating 4 [2',6,6'- trimethyl cyclohexen (1) yl] 2 methyl buten (2)- al (1) with an N-haloamide and heating the halogenated compound formed with a tertiary base to produce 4 [2',6',6'- trimethyl cyclohexen (2) ylidene]- 2 methyl buten (2) al (1).

9. A process as in claim 8 wherein the halogenating agent is 'N-bromosuccinimide, and the tertiary base is quinoline.

10. A process which comprises halogenating 6-[2,6',6- trimethyl cyclohex-en (1) yl] 4 methyl hexadien- (2,4) a1 (1) with an N-haloamide and heating the halogenated compound formed with a tertiary base to produce 6 [2',6,6'- trimethyl cyclohexen (2) ylidene] 4 methyl hexadien (2,4) a1 (l).

11. A process as in claim 10 wherein the halogenating agent is N-brornosuccinimide and the tertiary base is quinoline.

12. A process which comprises halogenating 8-[2 6',6'- trimethyl cyclohexen (1) yl] 2,6 dimethyl octatrien (2,4,6) al (1) with an N-haloamide and heating the halogenated compound formed with a tertiary base to produce 8-[2',6,6'-trimethyl-cyclohexen-(Z)-ylidene1-2,6-dimethyl-octatrien-(2,4,6)-al-(1).

13. A process as in claim 12 wherein the halogenating agent is N-bromosuccinimide and the tertiary base is quinoline.

No references cited. 

1. A PROCESS WHICH COMPRISES HALOGENATING BY MEANS OF AN N-HALOAMIDE A MEMBER OF THE GROUP CONSISTING OF 4-(2'',6'',6''- TRIMETHYL-CYCLOHEXEN -(1)-YL)-2-METHYLBUTEN -(2) -AL -(1), 6-(2,''6'',6'', -TRIMETHYL -CYCLOHEXEN(1) -YL)-4-METHYL-HEXADIEN -(2,4)-AL-(1),8-(2'',6'',6''TRIMETHYL-CYCLOHEXEN -71) -YL)-2,6-DIMETHYL -OCTATRIEN -(2,4,6) -AL - (1) AND ACETALS THEREOF AND HEATING THE HALOGEN COMPOUND FORMED WITH A TERTIARY BASE THEREBY DEHYDROHALOGENATING WITH CONCOMITANT ALLYL REARRANGEMENT.
 4. 6- (2'',6'',6''-TRIMETHYL - CYCLOHEXEN - (2) - YLIDENE)4-METHYL-HEXADIEN-(2,4)-AL-(1). 